The present invention relates to a device for repositioning with high accuracy a patient's skeleton and the area in the patient's body that is to be subjected to treatment, the position of the area being previously determined, for example by means of angiogram, PET, DSA, CT, MRI or X-ray equipment.
In radiotherapy as well as in surgical operations, the possibility of identifying the target area with great accuracy is highly important. To minimize the risk, the surgeon must be sure of hitting the correct area in the treatment.
It is vital that the treatment area can be easily and safely identified on different occasions, since, for example, fractionated radiation treatment requires a number of successive treatment sessions.
In radiation treatment of cancer, the intended tumor dose is given as repeated small radiotherapy doses during several weeks. It is thus important that in each treatment session the tumor in the patient is correctly positioned relative to the radiation field of the radiotherapy apparatus.
The prevalent method for positioning a patient's skeleton (body) is that the skin of the part of the body that is to be subjected to radiotherapy is marked with a felt-tip pen, with or without supplementary tattoo points. By means of skin marks and laser position beams, the nurse oncologist tries to arrange the patient in the correct position on the radiotherapy table in each treatment session. There is a drawback of the skin as outer reference for the tumor lying inside the body. The skin is elastic and moves freely relative to the parts of the skeleton. The movement of the skin with the uncertain position of the skin marks in relation to the parts of the skeleton makes it necessary to use safety margins on the radiation fields such that the tumor is not positioned outside the radiation field during treatment. The increased sizes of the fields result in normal tissues without cancer being unnecessarily irradiated. This causes higher radiation energy to the body and may lead to undesired side-effects of the radiotherapy. By irradiating greater volumes than necessary, the total radiation dose cannot in certain positions be increased to the desired level. It is desirable that adjustments of the patient's position on the radiotherapy table can be made more exactly.
A plurality of equipment and techniques are available to reduce deviations in the positioning of a patient, so-called fixtures such as masks, bite blocks, straps, plastic shells etc. The fixation aids should be usable in connection with the computerised axial tomography, the simulator and in the therapy room without affecting the levelling base or the radiotherapy. The problem with the fixation aids is that the patient who lies down in a fixture may on his own lie with his skeleton parts rotating in his own subcutaneous fat while the skin owing to its elasticity can be stretched in different directions, which results in the skin marks not representing the original position in relation to the tumor.
One object of the present invention is to provide a positioning device having high accuracy in identifying the target area.
A further object of the invention is to provide a positioning device which permits reliable and repeatable identification of the treatment area.
According to the invention, these objects are achieved by a device as described by way of introduction, which is characterized in that the device comprises a non-yielding, upright and radioparent panel element and a base plate, which in a substantially perpendicular fashion is fixedly connected to said panel element, of which at least the panel element comprises fixation means for fixing the patient in a given, essentially upright orientation to the panel element, and that the device also comprises wheel means mounted on the base plate for moving the panel element and the patient to a radiotherapy table, a tilting and conveying assembly being arranged at the end of the table for tilting the panel element together with the patient from the upright orientation to a lying orientation and conveying these to a defined place on the table.
The invention is based on the knowledge that the skin is affected by gravity as the position of the body changes. The thicker the subcutaneous fat, the greater the movements. Also the patient's movement of hips and other parts of the body is difficult to reproduce by today's techniques.
The positioning problem is solved by carrying out the settings when the patient is placed in an upright position. When a person is standing without clothes and shoes, the skin costume will have a special carriage in relation to the skeleton. The legs have a given length and the hip-joints will have a position relative to the floor surface which is the same from occasion to occasion. The skin will be stretched owing to gravity, but this stretching will be the same from occasion to occasion during a radiotherapy period, unless an extreme loss of weight takes place.
The patient places himself on a base plate whose rear part is connected to an upright panel behind the patient's back. This panel should be made of a light-weight material since it is to form the base for the patient during radiotherapy. When the patient takes his natural upright position for the first time, considers that he is standing straight on the base plate and feels that his body reaches the panel behind his back in a resting fashion, correctly positioned relative to the panel, the skin is marked in a suitable position of the body by means of laser position lights or some other technique connected to the panel and indicating a relationship between the back panel and the body. It is the relationship of the body to the panel that is decisive of the continued positioning.
It should thus be possible to attach various means to the panel, which like building bricks can be snapped onto the panel on various levels, be removed after positioning or remain during computerized axial tomography, magnetic resonance imaging, stimulation work or during radiotherapy. This may involve positioning marks, lateral supports, supports for the curve of the back, head-neck, straps, masks and other fixation aids, connected to the panel.
After positioning of the patient, the panel should, with a satisfactory sense of security for the patient, slowly tilt the patient backwards to a recumbent position. The panel can advantageously be arranged at the end of the radiotherapy table, be tilted over the table in the longitudinal direction to a horizontal position on the wire-cloth of the table and subsequently be advanced along the table by means of the wire-cloth of the table. After treatment, the movements are reversed and the patient can leave.
What has been said about the patient's supine position also applies to all the other positions of the body sideways, lying on the face or any other position.
The panel concerned should also be designed to be possible to move like a "domestic baking plate" from computerized axial tomography to a treatment apparatus arranged on some carriage which readily enables moving of the patient without any efforts made by the staff. This confers the advantage that the patient can remain without changing the position of the body in connection with precision radiotherapy.
The panel should be fitted with or be fittable with supplementary aids to make it possible to position the panel by its own reference system in relation to equipment in a diagnostic clinic and radiotherapy clinic. In this context, reference is made to Swedish Patent 9302066 disclosing a stereotactical instrument having an orienting means which is suitable to mount on the panel.
The panel can also be fitted with electronic components such as transceivers, magnets, light sources etc. which can indicate the position in relation to the room and equipment of different types, the position of the patient, the position of the radiation fields on the patient and against the panel or the means of the panel.
What has been said about moving the patient between examination and treatment also applies to a preparatory positioning of the patient on the panel before the radiotherapy room is available, thereby gaining time for radiotherapy in case of limited radiotherapy capacity so as to increase the capacity.
Further it is possible to use more than one panel in one treatment session by one panel being arranged behind the patient and one panel with accessories being mounted in front of the patient in connection with radiotherapy.
What has been said about the panel does not necessarily signify a flat panel. It can also be shaped like a bucket seat, adapted completely to the contour of the patient, or it may have any appearance whatsoever.
A variant of the panel can be formed with a hinge in the center so as to permit the upper half to be pivoted upwards when treating breast cancer such that the breast-bone will be horizontally positioned, if desired.